1. Field of the Invention
The present invention relates generally to removing obstacles in oil wells, gas wells, water wells, and from the annulus of other holes, by grinding and cutting the obstacle with a mill. Typically, the mill is attached to a mud motor that rotates the mill at high speed. Coiled tubing is often used to deliver fluid through the mud motor, through the mill, then up the annulus surrounding the coiled tubing to the surface. The circulating fluid, which is typically fresh water or salt water, transports the milled obstacle particles to the surface.
2. Description of the Prior Art
There have been mills available for several years that have several common features including a threaded top end for attachment to the mud motor, a neck, a body, several blades, a special grinding material attached to the blades to form tips, a central hole through the top end, the neck and body, leading to tip ports such that the circulation fluid exits the tip ports, and vertical watercourses on the body which generally provide a path for the circulation fluid to move from the tips and past the body. Carbide cutting inserts have been attached to the blades prior to adding the grinding material for better cutting performance.
No prior mills have optimally addressed the problem of milled particles clogging the tip ports, the vertical watercourses, and the annulus about the tips, body and neck, nor have prior mills optimized the number and configuration of the cutting inserts.
What is needed is a mill that maximizes the ability of the circulation fluid to remove milled particles from the mill to the surface, and optimizes the configuration of the cutting inserts.
The present invention is an improved mill for grinding and cutting obstacles in oil wells, gas wells, water wells, and from the annulus of other holes. Such obstacles can include plugs made from aluminum, cast iron, metal, and combined metals, as well as, cement and cemented coil tubing. The improvements overcome the shortcomings of the prior art by providing an improved ability of the circulation fluid to move milled particles from the mill to the surface.
One aspect of the improvement is to change the vertical configuration of the watercourses, to a helical configuration. This improvement substantially enhances the ability of the circulation fluid to carry milled particles from the mill tip area past the body. For the high rotation speed mill, this helical path cut in the body, allows a substantially smoother path for the milled particles to follow since the trailing edge of the watercourse presents a sloped face to the particles instead of a perpendicular face. The particles naturally follow the slope as the mill rotates, instead of being held against the watercourse trailing edge until more particles or circulation fluid forces them along the watercourse. The circulation fluid itself also moves through the helical watercourses with less turbulence, thus increasing its circulation rate.
Another enhancement to the circulation fluid""s ability to move the milled particles, is the provision of reverse ports. In prior art mills, all circulation fluid was required to exit through the mill ports. In the present invention reverse ports are provided that exit the central hole near the mid-point of the body, and then exit the body near the point where the watercourse terminates near the neck. Both the U-tube effect from the column of circulation fluid and the backpressure caused by the tip ports, result in a portion of the circulation fluid being forced through the reverse ports. This portion of the circulation fluid exits the mill and creates turbulence as it joins other circulation fluid moving along the annulus and through the watercourses. This turbulence aids in preventing accumulations of milled particles in the neck area.
The configuration of cutting inserts on the blades are also optimized.
A mill is provided for grinding objects in wells, the mill being of the type having an attachment end, a neck, a body, watercourses on the body, blades, tips formed from grinding material on the blades, a central hole through the neck, and body, and tip ports in fluid communication with the central hole such that fluids can be circulated through the mill, the mill being rotated during grinding in a generally counterclockwise direction when viewed from the bottom, wherein the improvement comprises, the watercourses, each watercourse having a first end, each first end being proximate a tip port, each watercourse further having a second end, each second end being proximate the neck, and further each watercourse being generally helical from the first end to the second end, the watercourse first end leading the second end during grinding.
The foregoing mill also comprises at least one cutting insert attached to one or more of the blades.
A mill is provided for grinding objects in wells, the mill being of the type having an attachment end, a neck, a body, watercourses on the body, blades, tips formed from grinding material on the blades, a central hole through the neck, and body, and tip ports in fluid communication with the central hole such that fluids can be circulated through the mill, wherein the improvement comprises, the body, the body further comprising at least one reverse port, each reverse port exiting the mill central hole from within the body, and exiting the mill at a point higher than the point of exit from the central mill hole.
The foregoing mill may also include at least one cutting insert attached to one or more blades.
The foregoing mill may also include each reverse port exiting the mill proximate the neck and proximate one of the watercourses.
A mill is provided for grinding objects in wells, the mill being of the type having an attachment end, a neck, a body, watercourses on the body, blades, tips formed from grinding material on the blades, a central hole through the threads, neck, and body, and tip ports in fluid communication with the central hole such that fluids can be circulated through the mill, wherein the improvement comprises means for enhanced displacement of milled particles from the mill tips.
In the foregoing mill, the watercourses may be generally vertical.
In the foregoing mill, the watercourses may be generally helical.
A mill is provided for rotationally grinding and cutting an object in a well, the apparatus being attached to a rotation source such that the mill is rotated, the mill further being in circulatory fluid communication with a source of fluid from the surface the mill being rotated during grinding and cutting in a generally counterclockwise direction when viewed from the bottom of the well, the device comprising: (a) a neck, the neck having a top end, the top end being attached to the rotation source; (b) a body attached to the neck, the body having a length, the body having exterior watercourses along the length of the body, the body and the neck each having a central hole, the neck central hole being aligned with the body central hole; and (c) a plurality of tips, each tip having a blade and grinding material attached to the blade, the blades being attached to the body, the grinding material having tip ports, the tip ports being in fluid communication with the body central hole, each watercourse further having a first end proximate one of the tip ports, and a second end proximate the neck, each watercourse being generally helical from such watercourse""s first end to second end the watercourse first end leading the second end during grinding and cutting.
The foregoing mill may further include the body, the body further having at least one reverse port, each reverse port exiting the body central hole and exiting the mill at a point which is higher than the point of exit from the body central hole.
The foregoing mill may also include at least two cutting inserts attached to each blade.
A mill is provided for rotationally grinding and cutting an object in a well, the apparatus being attached to a rotation source such that the mill is rotated, the mill further being in circulatory fluid communication with a source of fluid from the surface, the device comprising: (a) a neck, the neck having a top end, the top end being attached to the rotation source; (b) a body attached to the neck, the body having a length, the body having exterior watercourses along the length of the body, the body and the neck each having a central hole, the neck central hole being aligned with the body central hole, the body further having at least one reverse port, each reverse port exiting the body central hole and exiting the mill at a point which is higher than the point of exit from the body central hole; and (c) a plurality of tips, each tip having a blade and grinding material attached to the blade, the blades being attached to the body, the grinding material having tip ports, the tip ports being in fluid communication with the body central hole, each watercourse further having a first end proximate one of the tip ports.
The foregoing mill may also include the body watercourses, each watercourse further having a second end, each watercourse being generally helical from such watercourse""s first end to the second end.
The foregoing mill may also include at least two cutting inserts attached to each blade.
The foregoing and other advantages will appear from the description to follow. In the description reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawings, like reference characters designate the same or similar parts throughout the several views.
The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.